aarch64: Add vector implementations of log routines

Optimised implementations for single and double precision, Advanced
SIMD and SVE, copied from Arm Optimized Routines. Log lookup table
added as HIDDEN symbol to allow it to be shared between AdvSIMD and
SVE variants.

As previously, data tables are used via a barrier to prevent
overly aggressive constant inlining. Special-case handlers are
marked NOINLINE to avoid incurring the penalty of switching call
standards unnecessarily.

Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>

1 files changed, 173 insertions, 0 deletions

diff --git a/sysdeps/aarch64/fpu/v_log_data.c b/sysdeps/aarch64/fpu/v_log_data.c
new file mode 100644
index 0000000000..6fd6f43695
--- /dev/null
+++ b/sysdeps/aarch64/fpu/v_log_data.c
@@ -0,0 +1,173 @@
+/* Lookup table for double-precision log(x) vector function.
+
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include "vecmath_config.h"
+
+const struct v_log_data __v_log_data = {
+  /* Worst-case error: 1.17 + 0.5 ulp.
+     Rel error: 0x1.6272e588p-56 in [ -0x1.fc1p-9 0x1.009p-8 ].  */
+  .poly = { -0x1.ffffffffffff7p-2, 0x1.55555555170d4p-2, -0x1.0000000399c27p-2,
+	    0x1.999b2e90e94cap-3, -0x1.554e550bd501ep-3 },
+  .ln2 = 0x1.62e42fefa39efp-1,
+  /* Algorithm:
+
+	x = 2^k z
+	log(x) = k ln2 + log(c) + poly(z/c - 1)
+
+     where z is in [a;2a) which is split into N subintervals (a=0x1.69009p-1,
+     N=128) and log(c) and 1/c for the ith subinterval comes from two lookup
+     tables:
+
+	invc[i] = 1/c
+	logc[i] = (double)log(c)
+
+     where c is near the center of the subinterval and is chosen by trying
+     several floating point invc candidates around 1/center and selecting one
+     for which the error in (double)log(c) is minimized (< 0x1p-74), except the
+     subinterval that contains 1 and the previous one got tweaked to avoid
+     cancellation.  */
+  .invc = { 0x1.6a133d0dec120p+0, 0x1.6815f2f3e42edp+0,
+	    0x1.661e39be1ac9ep+0, 0x1.642bfa30ac371p+0,
+	    0x1.623f1d916f323p+0, 0x1.60578da220f65p+0,
+	    0x1.5e75349dea571p+0, 0x1.5c97fd387a75ap+0,
+	    0x1.5abfd2981f200p+0, 0x1.58eca051dc99cp+0,
+	    0x1.571e526d9df12p+0, 0x1.5554d555b3fcbp+0,
+	    0x1.539015e2a20cdp+0, 0x1.51d0014ee0164p+0,
+	    0x1.50148538cd9eep+0, 0x1.4e5d8f9f698a1p+0,
+	    0x1.4cab0edca66bep+0, 0x1.4afcf1a9db874p+0,
+	    0x1.495327136e16fp+0, 0x1.47ad9e84af28fp+0,
+	    0x1.460c47b39ae15p+0, 0x1.446f12b278001p+0,
+	    0x1.42d5efdd720ecp+0, 0x1.4140cfe001a0fp+0,
+	    0x1.3fafa3b421f69p+0, 0x1.3e225c9c8ece5p+0,
+	    0x1.3c98ec29a211ap+0, 0x1.3b13442a413fep+0,
+	    0x1.399156baa3c54p+0, 0x1.38131639b4cdbp+0,
+	    0x1.36987540fbf53p+0, 0x1.352166b648f61p+0,
+	    0x1.33adddb3eb575p+0, 0x1.323dcd99fc1d3p+0,
+	    0x1.30d129fefc7d2p+0, 0x1.2f67e6b72fe7dp+0,
+	    0x1.2e01f7cf8b187p+0, 0x1.2c9f518ddc86ep+0,
+	    0x1.2b3fe86e5f413p+0, 0x1.29e3b1211b25cp+0,
+	    0x1.288aa08b373cfp+0, 0x1.2734abcaa8467p+0,
+	    0x1.25e1c82459b81p+0, 0x1.2491eb1ad59c5p+0,
+	    0x1.23450a54048b5p+0, 0x1.21fb1bb09e578p+0,
+	    0x1.20b415346d8f7p+0, 0x1.1f6fed179a1acp+0,
+	    0x1.1e2e99b93c7b3p+0, 0x1.1cf011a7a882ap+0,
+	    0x1.1bb44b97dba5ap+0, 0x1.1a7b3e66cdd4fp+0,
+	    0x1.1944e11dc56cdp+0, 0x1.18112aebb1a6ep+0,
+	    0x1.16e013231b7e9p+0, 0x1.15b1913f156cfp+0,
+	    0x1.14859cdedde13p+0, 0x1.135c2dc68cfa4p+0,
+	    0x1.12353bdb01684p+0, 0x1.1110bf25b85b4p+0,
+	    0x1.0feeafd2f8577p+0, 0x1.0ecf062c51c3bp+0,
+	    0x1.0db1baa076c8bp+0, 0x1.0c96c5bb3048ep+0,
+	    0x1.0b7e20263e070p+0, 0x1.0a67c2acd0ce3p+0,
+	    0x1.0953a6391e982p+0, 0x1.0841c3caea380p+0,
+	    0x1.07321489b13eap+0, 0x1.062491aee9904p+0,
+	    0x1.05193497a7cc5p+0, 0x1.040ff6b5f5e9fp+0,
+	    0x1.0308d19aa6127p+0, 0x1.0203beedb0c67p+0,
+	    0x1.010037d38bcc2p+0, 1.0,
+	    0x1.fc06d493cca10p-1, 0x1.f81e6ac3b918fp-1,
+	    0x1.f44546ef18996p-1, 0x1.f07b10382c84bp-1,
+	    0x1.ecbf7070e59d4p-1, 0x1.e91213f715939p-1,
+	    0x1.e572a9a75f7b7p-1, 0x1.e1e0e2c530207p-1,
+	    0x1.de5c72d8a8be3p-1, 0x1.dae50fa5658ccp-1,
+	    0x1.d77a71145a2dap-1, 0x1.d41c51166623ep-1,
+	    0x1.d0ca6ba0bb29fp-1, 0x1.cd847e8e59681p-1,
+	    0x1.ca4a499693e00p-1, 0x1.c71b8e399e821p-1,
+	    0x1.c3f80faf19077p-1, 0x1.c0df92dc2b0ecp-1,
+	    0x1.bdd1de3cbb542p-1, 0x1.baceb9e1007a3p-1,
+	    0x1.b7d5ef543e55ep-1, 0x1.b4e749977d953p-1,
+	    0x1.b20295155478ep-1, 0x1.af279f8e82be2p-1,
+	    0x1.ac5638197fdf3p-1, 0x1.a98e2f102e087p-1,
+	    0x1.a6cf5606d05c1p-1, 0x1.a4197fc04d746p-1,
+	    0x1.a16c80293dc01p-1, 0x1.9ec82c4dc5bc9p-1,
+	    0x1.9c2c5a491f534p-1, 0x1.9998e1480b618p-1,
+	    0x1.970d9977c6c2dp-1, 0x1.948a5c023d212p-1,
+	    0x1.920f0303d6809p-1, 0x1.8f9b698a98b45p-1,
+	    0x1.8d2f6b81726f6p-1, 0x1.8acae5bb55badp-1,
+	    0x1.886db5d9275b8p-1, 0x1.8617ba567c13cp-1,
+	    0x1.83c8d27487800p-1, 0x1.8180de3c5dbe7p-1,
+	    0x1.7f3fbe71cdb71p-1, 0x1.7d055498071c1p-1,
+	    0x1.7ad182e54f65ap-1, 0x1.78a42c3c90125p-1,
+	    0x1.767d342f76944p-1, 0x1.745c7ef26b00ap-1,
+	    0x1.7241f15769d0fp-1, 0x1.702d70d396e41p-1,
+	    0x1.6e1ee3700cd11p-1, 0x1.6c162fc9cbe02p-1 },
+  .logc = { -0x1.62fe995eb963ap-2, -0x1.5d5a48dad6b67p-2,
+	    -0x1.57bde257d2769p-2, -0x1.52294fbf2af55p-2,
+	    -0x1.4c9c7b598aa38p-2, -0x1.47174fc5ff560p-2,
+	    -0x1.4199b7fa7b5cap-2, -0x1.3c239f48cfb99p-2,
+	    -0x1.36b4f154d2aebp-2, -0x1.314d9a0ff32fbp-2,
+	    -0x1.2bed85cca3cffp-2, -0x1.2694a11421af9p-2,
+	    -0x1.2142d8d014fb2p-2, -0x1.1bf81a2c77776p-2,
+	    -0x1.16b452a39c6a4p-2, -0x1.11776ffa6c67ep-2,
+	    -0x1.0c416035020e0p-2, -0x1.071211aa10fdap-2,
+	    -0x1.01e972e293b1bp-2, -0x1.f98ee587fd434p-3,
+	    -0x1.ef5800ad716fbp-3, -0x1.e52e160484698p-3,
+	    -0x1.db1104b19352ep-3, -0x1.d100ac59e0bd6p-3,
+	    -0x1.c6fced287c3bdp-3, -0x1.bd05a7b317c29p-3,
+	    -0x1.b31abd229164fp-3, -0x1.a93c0edadb0a3p-3,
+	    -0x1.9f697ee30d7ddp-3, -0x1.95a2efa9aa40ap-3,
+	    -0x1.8be843d796044p-3, -0x1.82395ecc477edp-3,
+	    -0x1.7896240966422p-3, -0x1.6efe77aca8c55p-3,
+	    -0x1.65723e117ec5cp-3, -0x1.5bf15c0955706p-3,
+	    -0x1.527bb6c111da1p-3, -0x1.491133c939f8fp-3,
+	    -0x1.3fb1b90c7fc58p-3, -0x1.365d2cc485f8dp-3,
+	    -0x1.2d13758970de7p-3, -0x1.23d47a721fd47p-3,
+	    -0x1.1aa0229f25ec2p-3, -0x1.117655ddebc3bp-3,
+	    -0x1.0856fbf83ab6bp-3, -0x1.fe83fabbaa106p-4,
+	    -0x1.ec6e8507a56cdp-4, -0x1.da6d68c7cc2eap-4,
+	    -0x1.c88078462be0cp-4, -0x1.b6a786a423565p-4,
+	    -0x1.a4e2676ac7f85p-4, -0x1.9330eea777e76p-4,
+	    -0x1.8192f134d5ad9p-4, -0x1.70084464f0538p-4,
+	    -0x1.5e90bdec5cb1fp-4, -0x1.4d2c3433c5536p-4,
+	    -0x1.3bda7e219879ap-4, -0x1.2a9b732d27194p-4,
+	    -0x1.196eeb2b10807p-4, -0x1.0854be8ef8a7ep-4,
+	    -0x1.ee998cb277432p-5, -0x1.ccadb79919fb9p-5,
+	    -0x1.aae5b1d8618b0p-5, -0x1.89413015d7442p-5,
+	    -0x1.67bfe7bf158dep-5, -0x1.46618f83941bep-5,
+	    -0x1.2525df1b0618ap-5, -0x1.040c8e2f77c6ap-5,
+	    -0x1.c62aad39f738ap-6, -0x1.847fe3bdead9cp-6,
+	    -0x1.43183683400acp-6, -0x1.01f31c4e1d544p-6,
+	    -0x1.82201d1e6b69ap-7, -0x1.00dd0f3e1bfd6p-7,
+	    -0x1.ff6fe1feb4e53p-9, 0.0,
+	    0x1.fe91885ec8e20p-8,  0x1.fc516f716296dp-7,
+	    0x1.7bb4dd70a015bp-6,  0x1.f84c99b34b674p-6,
+	    0x1.39f9ce4fb2d71p-5,  0x1.7756c0fd22e78p-5,
+	    0x1.b43ee82db8f3ap-5,  0x1.f0b3fced60034p-5,
+	    0x1.165bd78d4878ep-4,  0x1.3425d2715ebe6p-4,
+	    0x1.51b8bd91b7915p-4,  0x1.6f15632c76a47p-4,
+	    0x1.8c3c88ecbe503p-4,  0x1.a92ef077625dap-4,
+	    0x1.c5ed5745fa006p-4,  0x1.e27876de1c993p-4,
+	    0x1.fed104fce4cdcp-4,  0x1.0d7bd9c17d78bp-3,
+	    0x1.1b76986cef97bp-3,  0x1.295913d24f750p-3,
+	    0x1.37239fa295d17p-3,  0x1.44d68dd78714bp-3,
+	    0x1.52722ebe5d780p-3,  0x1.5ff6d12671f98p-3,
+	    0x1.6d64c2389484bp-3,  0x1.7abc4da40fddap-3,
+	    0x1.87fdbda1e8452p-3,  0x1.95295b06a5f37p-3,
+	    0x1.a23f6d34abbc5p-3,  0x1.af403a28e04f2p-3,
+	    0x1.bc2c06a85721ap-3,  0x1.c903161240163p-3,
+	    0x1.d5c5aa93287ebp-3,  0x1.e274051823fa9p-3,
+	    0x1.ef0e656300c16p-3,  0x1.fb9509f05aa2ap-3,
+	    0x1.04041821f37afp-2,  0x1.0a340a49b3029p-2,
+	    0x1.105a7918a126dp-2,  0x1.1677819812b84p-2,
+	    0x1.1c8b405b40c0ep-2,  0x1.2295d16cfa6b1p-2,
+	    0x1.28975066318a2p-2,  0x1.2e8fd855d86fcp-2,
+	    0x1.347f83d605e59p-2,  0x1.3a666d1244588p-2,
+	    0x1.4044adb6f8ec4p-2,  0x1.461a5f077558cp-2,
+	    0x1.4be799e20b9c8p-2,  0x1.51ac76a6b79dfp-2,
+	    0x1.57690d5744a45p-2,  0x1.5d1d758e45217p-2 }
+};